Method of determining yield loss due to a combination of defects in manufacturing method utilizing same

ABSTRACT

A method of inspecting defective manufactured units and determining for any selected combination of defect categories the respective probable number of units having only a defect in each category of the selected combination of categories, and also the yield loss due to the selected combination of categories. The defect categories are arranged in an ordered sequence. Each unit of a sample of the manufactured units is inspected for the presence of a defect in each successive one of the ordered sequence of defect categories. As soon as it is determined that an inspected unit has a defect in a particular category, all further inspection of the unit is omitted and the unit is not inspected for the presence of defects in the subsequent categories of the sequence. From the resulting data there is determined for the selected combination of defect categories the respective probable number of units having only a defect in each category of the selected combination of categories and no defect in other categories. There is also determined for the selected combination of categories of defects the yield increase that may be expected by a change in the manufacturing process to eliminate the manufacture of any units having defects in the selected combination of categories. A manufacturing method utilizing this inspection method and the yield determinations is also disclosed.



